It hovered in the sky over the city for more than 30 minutes before it landed at the Sardar Vallabhai Patel International Airport here at 11.25 PM, fifteen hours after it took off from Muscat this morning.

"This project is about saving energy, so making the plane light is paramount," said project co-founder and co-pilot of SI-2 Andre Borschberg.

"Ahmedabad is a very important stop...I am impressed by Gujarat's dynamism in terms of renewables," said Borschberg who reached the city earlier today, while the SI-2 was flown by co-founder Bertrand Piccard from Muscat.

Piccard and Borschberg are likely to stay in the city for two to three days before leaving for Varanasi.

The aircraft is also likely to hover above Ganga river in Varanasi to spread the message of cleanliness and clean energy, an official associated with the project said.

Solar Impulse is claimed to be the first aircraft to fly day and night without a drop of fuel, propelled solely by the sun's energy. The single-seater aircraft, made of carbon fibre, has a 72 meter wingspan, larger than that of Boeing-747 and weighs only 2,300 kg.

The 17,248 solar cells on the wing recharge four lithium polymer batteries weighing 633 kg each, which allow the aircraft to fly at night.

It reached Muscat yesterday. It took nearly 13 hours to reach Muscat from Abu Dhabi.

From Varanasi it will fly to Mandalay in Myanmar and Chongqing and Nanjing in China and thereon to USA.